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QUESTION: hi sir, I have problem in fabricating COIR COMPOSITE with VINYLESTER as a resin...I am using weight fraction and hand layup method...upto 10% by weight of fibre addition using hand layup is easy but adding more than that is not possible to mix it properly and pour it evenly ..what I should do to do up to 50% by weight of fibre. Fibre-chopped coir,resin-vinylester,percentages 10%,20%,30%,40%,50%,hand layup method

ANSWER: Hi Vasant,

So to get 10% fibre fraction, thats 90 grams of resin to 10 grams of fibre.
To get 20% fibre fraction, thats 80 grams of resin to 20gms of fibre.  I'm sure you get the idea there.

I find the easiest way to hand lay fibre is to brush down a layer of mixed / catalysed resin only, then lay the fibre into this wet surface, then add more resin on top with a brush or mini-roller, then consolidate with a hard roller, either washer type or bristle type depending on your fibre type - what fibre type is it?

If using woven cloth, its also a good idea to use a squeegee to  move the resin around and wet-out the fibre completely.   If this is what you have already tried, I'd usggest either finding a lower viscosity laminating resin (easy with vinylester) or perhaps adding up 10% by weight of Styrene Monomer solution to the MIXED resin.  Be careful with this, you are altering hte resin chemistry, and perhaps start with 5% to see what effect it may have on cure times, and cured properties.

From what you have said, it sounds like you are almost making a Bulk Moulding compound by mixing the fibre into the resin and then attempting to pour it out - this is very hard to do without using a heavy pressure and/or vacuum equipment.

I hope this helps,

Regards,
Andy

---------- FOLLOW-UP ----------

QUESTION: u r right I m making bulk moulding which is difficult to do...even I tried by laying up layer wise as you mentioned it is not fitting into my 10mm thickness mould size it oversize which require a heavy press to make accommodate in the mould size otherwise it is not at all possible....I wonder how others r u doing using hand layup....can you give reference for me so that by reading that I can understand how others r u doing and what I m lagging in my process..

Answer
HI Vasant,

I would recommend using a lower viscosity resin, and matched die mouldning at a minimum to get your 10mm thick lamainate.  Lots of pressure (a press, or light mechanical press and vacuum - VARTM-type technique) could be used to get the product to flow or extrude, but this involves significant cost.

Suggest you try to google "Bulk or Sheet Moulding Composites" and go from there.

I hope this helps,

Regards,
Andy

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andy mackay

Expertise

Composite fabrication and testing, plug and mould design & build, surfacing materials, gelcoats, resins (epoxy, polyester, BMI, urethane) GRP, FRP, carbon, aircraft and marine composites, infusion techniques, Light RTM methodology, troubleshooting materials and process engineering.

Experience

11 yrs experience with aeronautical, marine and bathroomware composites.

Education/Credentials
Royal New Zealand Air Force Advanced Composites Course BCA Victoria University, Wellington, 1995

Past/Present Clients
Aeronautical, marine and bathroom ware composite cmanufacturing.

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